Upper Block Coal Member


Brazil Formation,

Pennsylvanian System

Type locality and use of name: The name Upper Block Coal was first used formally by Ashley (1909, p. 57-58), who earlier (1899, p. 90, 103) had cited the term upper block coal as an informal usage. In 1899 this coalbed was also designated Coal IV in the sequence in northern Clay County and in Vigo County, where Ashley had based his numbering of Indiana coalbeds. Numerous descriptions of this coal from deep mines and outcrops around Brazil suggest that the type locality is about 2 to 3 miles (3 to 4.5 km) northeast of Brazil near the old mining town of Cardonia. Because the name Upper Block Coal has long commercial and geologic applications, Indiana coal stratigraphers continue to use the term. As advocated by Powell (1968), the Upper Block has member status in the Brazil Formation.

Description: In northern Clay County (Hutchison, 1960, p. 17-18), the Upper Block Coal Member consists of moderately dull banded hard semisplint. In mining it comes up in blocks measuring 0.5 foot (0.15 m) to more than 3.0 feet (0.9 m) on a side. This characteristic, as for the Lower Block Coal Member, results from two well-developed sets of vertical joints that trend about N. 201 W. and N. 701 E. In this area the Upper Block coal ranges from 1.5 to 5.0 feet (0.5 to 1.5 m) in thickness and averages slightly more than 3 feet (> 0.9 m) where mined. About 1.5 feet (0.b m) above the base of the coalbed is a zone of soft flaky coal (fusain) 0.01 to 0.03 foot (0.003 to 0.01 m) thick, which divides the coal into two benches of unequal thickness. The lower bench tends to break up into small cubes, but the upper bench breaks into larger blocks. In places the top few inches of the bed is a bone coal.

The roof of the coal is generally gray shale that is hard, silty, and thick bedded, but in places it is a few inches of gray soft flaky shale overlain by brown or gray sandstone that is hard, medium grained, and massive. In some small areas the sandstone forms the roof of the coal. The floor is gray underclay that is hard, slightly sandy, and carbonaceous and that becomes plastic when moistened.

Correlation: The Upper Block Coal Member, lying near the middle of the Brazil Formation, about 25 feet (7. 6 m) above the Lower Block and 20 to 25 feet (6.1 to 7.6 m) below the Minshall Coal Member, has been recognized from northern Fountain County (Hutchison, 1961) through Parke and Clay Counties (Hutchison, 1956, 1960, 1976), western Owen County, and Greene County (Kottlowski, 1959,1960; Hutchison and Hasenmueller, in preparation). A coalbed of different physical characteristics, which has been mapped as an unnamed coal in the Brazil Formation, is present in the same stratigraphic position in Daviess, Dubois, and Spencer Counties. This coalbed may be the Upper Block Coal Member, but lithostratigraphic continuity of this coal with the Upper Block type area has not been demonstrated

The Upper Block Coal Member has been variably correlated with the Pope Creek, Delwood, and Willis Coal Members in the different parts of the Illinois coalfield, with the Dry Wood Coal of Missouri, and with the Ice House (No. 3 Coal) and Elm Lick Coals of western Kentucky (Wanless, 1939, p. 105; Kosanke and others, 1960, pl. 1; Hopkins and Simon, 1975, p. 182-183; Peppers and Popp, 1979, p. 68-70; Searight, 1979, p. 84).

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